An infinitely long hollow conducting cylinder with inner radius `(r )/(2)` and outer radius `R` carries a uniform current ra density along its length . The magnitude of the magnetic field , ` | vec(B)|` as a function of the radial distance `r` from the axis is best represented by

Options

A.
B.
C.
D.

Answer

d

Explanation

From the centre up to a distance of `x = R//2`, the magnetic field will be zero and then onwards it increases up to the surface and then decreases inversely proportional to the distance. Hence, option (d) is correct.